1、微调：个人画笔在最上面

lib/components/white_board/white_board.dart

@@ -100,7 +100,7 @@ class _FWhiteBoardState extends State<FWhiteBoard> {
               CustomPaint(
                 size: MediaQuery.of(context).size,
                 painter: WhiteBoardPainter(
-                  pen: myPen,
+                  pen: otherPen,
                   width: canvasWidth,
                   height: canvasHeight,
                 ),
@@ -108,7 +108,7 @@ class _FWhiteBoardState extends State<FWhiteBoard> {
               CustomPaint(
                 size: MediaQuery.of(context).size,
                 painter: WhiteBoardPainter(
-                  pen: otherPen,
+                  pen: myPen,
                   width: canvasWidth,
                   height: canvasHeight,
                 ),